Shoplifting and other theft prevention has always been an important aspect for successful operation of any wholesale or retail sales facilities. Recent advances in automatic article identification technology provide these facilities with an improved means for detecting when an article is being shoplifted. One such method, Electronic Article Surveillance (“EAS”), typically includes an EAS detector and EAS devices commonly called labels, tags or transponders. The EAS detector transmits a radio-frequency (“RF”) carrier signal to any EAS device within a certain range of the detector. An active EAS device responds to the carrier signal by generating a response signal of a predetermined frequency, which triggers an alarm when received at the detector. For example, an active magneto-acoustic EAS tag resonates at a predetermined frequency when stimulated by an interrogation signal. When a customer purchases an item that is protected by an active EAS tag, a cashier typically deactivates the tag using deactivator that produces a magnetic deactivation field that alters the resonant frequency characteristic of the tag so that it no longer resonates at the predetermined frequency. The item may then be removed from the store without triggering an alarm.
A common method for shoplifting involves the collusion between a cashier and a customer known to the cashier to deactivate tags on items that have not actually been purchased. This method is referred to in the industry as “sweet-hearting.” Sweet-hearting takes place when a cashier scans or “rings up” one item and uses a deactivator to deactivate the EAS tag or label on more than one item. Generally, the cashier will physically “piggy-back” one item on top of another item so that a bar code scanner reading the universal product code (“UPC”) label will only detect the lower item, i.e., the item whose UPC label faces the bar code scanner. The cashier then passes the items over the deactivator, which deactivates both items simultaneously by transmitting an RF signal that both EAS tags receive. Often the item that is actually scanned and paid for is a low-cost item and the item that is simultaneously deactivated and not paid for is a high cost item. This shoplifting technique is difficult to visually detect because the cashier appears to be properly scanning and deactivating products. It is very difficult to determine that two items have been deactivated while only one has been purchased.
There are currently methods that prevent deactivation of EAS labels without scanning. These usually involve disabling the EAS deactivator until an item has been scanned. However, this method does not prevent sweet-hearting, it only prevents the occurrence of more than one deactivation process per scan.
Additionally, video monitoring may also used to try to detect sweet-hearting. The disadvantage of video methods is that they require surveillance personnel to manually review video tape to find evidence. Also, cashiers or service personnel that actually commit these sweet-hearting acts may be quite adept at concealing their actions from video surveillance, thus, even the most prudent observer may not detect the action.
Therefore, what is needed is a method to automatically detect the simultaneous deactivation of multiple EAS labels so that suspicious transactions may be identified.